There are many tubular tissues, such as a blood vessel, a bile duct, a ureter, and an esophagus, in the body. A specific disease such as a stricture or occlusion can occur. A disease such as a stricture, occlusion, aneurysm, or varix can also occur in the blood vessel. In particular, the aneurysm is a serious disease to cause massive bleeding when the aneurysm is ruptured. The aneurysm need to be treated immediately. Various instruments have been developed to perform an effective treatment.
In recent years, a metal cylindrical instrument called a stent has been often used to treat the stricture or aneurysm in a blood vessel. To treat the stricture, the stent is housed in a sheath or catheter (hereinafter, called a sheath) and is then conveyed to an affected part. After reaching the affected part, the stent is removed from the sheath. The stent whose diameter is expanded by a balloon enlarges the stricture and is then indwelled for treatment. To treat an aortic aneurysm, a stent graft in which the stent is covered by an artificial blood vessel is indwelled in the aneurysm. The stent graft resists the pressure of blood. In this manner, the aneurysm is treated so as to prevent the action of the pressure thereon.
There are provided a mesh stent using a metal cylinder formed in mesh and, as described in Patent Documents 1 and 2, a loop stent using a loop, in which its overall shape is formed cylindrically by bending a wire in a round rod shape in a zigzag and then joining the ends of the wire.
As the stent which is indwelled in an affected part whose curved state and thickness are different between patients, there has been typically used a complex stent in which a plurality of loop stents are arranged in a longitudinal direction according to the curved state of the affected part and the loop stents are joined to each other by a wire called a strut.
As described in Patent Documents 1 and 2, a joining portion which joins the stent main wire and the strut of the stent is configured as follows. The stent main wire in a target portion of the loop stent is molded flat. The end of the strut is molded flat. The molding portions are overlapped with each other for being fitted into a pipe formed in a substantially rectangular shape. The pipe is then caulked.
The stent whose diameter is reduced is fitted into the sheath and is then conveyed to an affected part. Upon reaching the affected part, the stent is removed from the sheath. The diameter of the stent is expanded by the balloon or by itself. The stent whose diameter is expanded in the affected part is brought into contact with the inner wall surface of a blood vessel corresponding thereto, thereby treating the blood vessel.
Patent Document 1: Japanese Patent Application Laid-Open No. 2003-062087
Patent Document 2: Japanese Patent Application Laid-Open No. 2004-097382